Heat-interchange apparatus and method of constructing the same



June 5, 1928.

G. CAHILL HEAT INTERCHANGE. APPARATUS AND METHOD OF GONSTR-UCTING THE SAME Filed March 12 1926 Fig.1.

lnvenior: 9832a L aZiZZf 6 147? 7 Patented June 5, 1928 UNITED STATES 1,672,708 PATENT OFFICE.

QERALD CAHILL, OF LOWE-LI, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO WINCHESTER REPEATING ARMS COMPANY, 01' NEW HAVEN, CONNECTICUT, A

CORPQBATIONQF CONNECTICUT.

HEAT-INTERCHANGE APPARATUS AND METHOD OF CONSTRUCTING THE SAME.

Application filed. March 12, 1926. Serial m. 94,274.

This invention relates to heat interchange apparatus and more particularly to apparatus comprising a fluid containing chamber separated from a second fluid containing 'space by a series of relatively thin contacting walls, such, for example, as may be afi'orded by a cellular or tubular structure, through which a fluid may be caused. to C11- culate and to effect a heat interchange with a second fluid in contact with the opposite sides of the walls thereof.

In constructing such an apparatus it is customary to form a core'by the assemblage .of thin walled tubular conduits having enlarged ends arranged in closel fitting relation and bonded together to orm pressure fluidtight front and rear" walls, the sides of such structure being closed in by suitable side walls also bonded to the enlarged tubuhr ends to form pressure fluid tightjoints thereat. It is often required to equip such a structure'with a chamber at the inlet or outlet ends, or both, in the form of a header comprising a tank or box-like compartment, the walls of which are relativelythick as compared with the walls of the tubular conduits.

Such a header, where it forms the top or bottom of the structure, must also be bonded to thetubular members, and where it is attached directly thereto as a subsequent operation to the bonding of the tubes/it requires the application of such high heat thatthe soldered joints of the adjacent tubes tend to be weakened.

One object of the invention is to provide such a construction that the attachment of the header may be effected without weakening the adjacent soldered joints of the tubes. The invention will be best understood by reference to the following description when taken in connection with the accompanying illustration of one specific 'embodiment'thereof, while its scope will be more particularly pointed out in the appended claims.

In the drawings,

Fig. 1 is a plan view of a heat interchange apparatus embodying one form of the invention with the header tank removed;

60 Fig.2 is a front elevation in partial section of the apparatus shown in Fig.1, with both the inlet and return headers in position and Fig. 3 is a cross sectional elevation on the line 3--3 in Fig.

Referring to the drawings and to the illustrative embodiment of the invention, I have there shown a heat interchange apparatus in the form of a heater comprising a steam chamber traversed by a multiplicity of air circulation tubes, the tubes being assembled site end it is enlarged for a shortfdistance into a head 7 non-circular or polygonal in cross section, and herein hexagonal in shape. The heads when grouped or assembled are arranged in close fitting contacting relation, while the intermediate portions of reduced circular cross section are separated by narrow connecting spaces 9 formin in the ag-' gregate the steam heating cham er.

A- group of such tubes are assembled in any desired geometrical arrangement, such as the rectangular form herein shown, the sides of the heater being closed in by any suitable means. Herein thesides are-formed by the two side closing strips 11 of copper or other suitable metal, and of a. width substantially coextensive with the length of the tubes, each strip being formed with corrugations or channels which fit over and against the contour ofv the hexagonal heads of the tubes, as shown in Fig. 2.

The depressions in the side closing strips 11 are filled withtubu ar members fitting the same, herein in the approximate cross sectional form of a D, thereby providing a substantially flat side against which there is placed a side stifi'ening plate 13. The latter, together with the closing strips 11, extends slightly beyond the assembled tubes both at the top and bottom of the heater. Theenlarged ends of the tubes in the to and bottom row are preferably given sucli a cross sectional shape (herein pentagonal) as to provide a flat top or bottom wall or shelf at the front and rear sides to which the tubular structure described, I interpose between the thick-walled. header and the thin-walled tubes intermediate separating strips of metal of a thickness less than the thickness of the walls of the header and preferably approximating as nearly as possible the density and thickness of the metal of the tubes.

In the disclosed embodiment of the invention these vintermediate metallic strips are provided by the walls of a false or skeleton tank 21 having box-like sides adapted to fit between the projecting ends of the strip 11- and presenting a space into which the sides of the header tank 15 fit and may be inserted. The bottom of the skeleton tank has openings 23 of ample area to prevent an obstruction of the flow of steam from the header into the heating chamber, the openings being separated by stiffening portions 25 which add to the rigidity and strength of the structure.

In constructing the heater the parts are first assembled and bonded without the top and bottom headers. Preferably the entire structure, omitting the headers and including the tubes, the side closing strips 11, stiffening strips 13 and skeleton tanks 21 held in closely fitting assembled relation as described, is subjected as an entirety to a single bonding operation. This may be accomplished by first successively dipping the opposite sides of the header structure into,

a bath containing a suitable flux, such, for example, as one employing a zinc chloride base, after which th opposite sides of the assembled structure are dipped in a bath of melted solder, causing the latter to bind together the various parts. The dipping process is preferably carried out so as to cause both the flux and solder to penetrate into the joints for a depth at least equal to the length of the 'hexagona1 heads of the tubes, the result being that the hexagonal heads are united with steam tight oints and all joints at the front and rear of the structure are similarly made pressure tight.

Since the false tanks are dipped with the core or matrix composed of the tubes, and since the thickness of the walls of the false tanks approximate that of the tubes, a uni- .form and more enduring bond is efiected than if it were attempted to bond the thick walls of the header directly to the tubes,

this being due to the fact that where parts of widely varying thickness are bonded by the dipping process the temperature of the two members of different thickness between which the bond is to take place is apt to difl'er or bonding operation to the walls of thefalse or skeleton tank without danger of transmitting suflicient heat to weaken the soldered joints of the adjacent tubes, theref by completing the construction of the heater.

e I may construct the heater preparatory to applying the headers by buildingit up through successive bonding operations, as by first bonding the tubes in the form of a matrix or core and then subsequently solder ing to such core the closing strip, the stiifening strip, and then the false tanks, and finally soldering the header tanks in position. The interposition of-the walls of the skeleton tank of a thickness or density inter-- mediate that of the walls of the header tank and the thin walls of the tube even, under this method of construction, affords the advantage of preventing such a transmission of heat to the thin walls of the tubes during the soldering of the header as would tend to weaken the joints.

The presence. of the skeleton tank'also stifi'ens the construction of the-assembled headers and tubes, preventing bulging and lessening the chances'of the structure under pressure tending to pull apart at the seams.

The use of the intermediate strips, herein in the form of the skeleton tank, however, has the important advantage that the entire structure, minus the headers, may be subjected to the. single bonding operation by the dipping process, which I prefer to'use, the subsequent bonding of the headers to the false tank being easily' accomplished with the production of a uniform bond at all the joints.

While I have herein shown and described for the purpose of illustration one specific embodiment of the invention, it is to be understood that the same may be varied withinwide limits, all. without departing from the spirit thereof. i

I claim:

1. A heat interchange apparatus having a heat interchange chamber formed by a group of thin walled tubular members extending through the chamber and having opposite enlarged ends arranged in closely fittm relation and bonded together to form ront and'rear walls of the chamber, a relatively thick walled header providing a fluid receiving chamber, and an intermediate member bonded to the tubes and to which said header is bonded, said intermediate member comprising a skeleton tank with box-like sides in which said header fits.

' 2. A heat interchan e apparatus having a heat interchan e cham r formed by a group of thin walle tubular members extending through the chamber and having opposite enlarged ends arranged in closely fittln relation and bonded to ether to form ront and rear walls of the chamber, a fluid receiving chamber at one end of the apparatus having relatively thick walls, and a member operation and the thick walled chamber bonded to the intermediate member by another bonding operation.

3. A heat interchange apparatus comprising a core formed of thin walled tubular members, a relatively thick walled header presenting a fluid receiving chamber at one end of the apparatus, and a; skeleton member havin walls of a thickness morenearly approximating the thickness of the walls of the tubular members interposed between and separating the walls of the thick walled header from the thin walled tubular members and serving to brace the structure, said parts being bonded together to form fluid tight joints, whereby the tubular members and the skeleton member may be bonded together by one bonding operation and the skeleton member bonded to the thick walled header by another bonding operation.

In testimonywhereof, I have signed my name to this specification.

, GERALD CAHILL. 

